Ascochyta Leaf and Pod Spot - Beans
Ascochyta on a bean stem, close up of lesions on a bean leaf & bean leaf symptoms
Pathogen
Fungus
Hosts
Field and broad beans
Symptoms
Brown / black leaf and pod spots with slightly sunken, grey centres and a brown margin, or red/brown and elongated stem lesions. Pycnidia in the lesions release spores which are spread by rain or wind-borne water droplets.
Development
This seed and trash-borne disease infects both winter and spring crops. Spores (conidia) from infected plants can then be further dispersed throughout the surrounding crop by rain splash and wind.
Favourable Factors
Cool, wet weather.
Importance
On beans severe stem lesions can weaken the stem, cause lodging and kill infected plants. Infected beans are usually stained and may be unsuitable for processing or use as seed.
Control
Some varieties do offer a degree of tolerance
Adopt short crop rotations.
Remove crop debris after harvest.
Seed should be tested for Ascochyta infection levels before drilling
Fungicide seed treatment.
Foliar fungicides are available for Ascochyta control
Close up of lesions on a bean leaf
Ascochyta on bean stem
